Prior anti-inflammatory agents of non-steroid type are effective to the improvement in the early stages of rheumatism and acute inflammation, however, have some defects of being no effective to progressed rheumatic diseases such as osteonecrosis, the improvement in chronic rheumatic diseases, or the treatment of arthrosteitis etc., and of having potent activities to induce gastric ulcer caused by the inhibition of the production of prostaglandin E.sub.2 (PGE.sub.2).
Recently it has been revealed that leukotriene (LT), esp. LTB.sub.4 etc., which is a metabolite produced via the metabolism of arachidonic acid caused by 5-lipoxygenase, is an important mediator in inflammation reaction. Furthermore, it has been suggested that the cause of inflammation relates to IL-1 which is a kind of cytokines and that also chronic rheumatism is much influenced by cytokines such as IL-1.
In view of circumstances above, attentions have been paid to compounds having inhibitory activities against the production of LTB.sub.4 and IL-1, as a new type of anti-inflammatory agent. These compounds are much useful than known non-steroidal anti-inflammatories, in respect of that they are expected to have efficacy not only to acute inflammation but also to chronic inflammation, e.g., chronic arthrorheumatism etc.
With an intention to develop such anti-inflammatory agents as described above, a wide variety of compounds are disclosed in specifications of Kokai 58-79944, Kokai 61-257967, Kokai 62-42977, Kokai 1-305028, Kokai 2-4729, Kokai 2-256645, Kokai 2-270865, and Kokai 1-503782.
As stated above, it has been desired to develop anti-inflammatory agents capable of inhibiting the production of mediators relating to inflammation such as PGE.sub.2, LTB.sub.4, and IL-1, however, such an anti-inflammatory agent as being useful for treating chronic inflammation and having little side effect, e.g., stomach disease, has not been developed yet.